1. Field of the Invention
The present invention relates to a zoom lens system.
2. Related Background Art
Among negative-positive type two-group zoom lenses, there is a zoom lens using an advanced Gauss type lens group as a second lens group having positive refractive power (disclosed, for example, in Japanese Patent Application Laid-Open No. 55-60911) In addition, zoom lenses of this type have been disclosed, for example, in Japanese Patent Application Laid-open Nos. 8-334694, 9-171140, 2000-28:37, and 2002-6214).
However, the zoom lens disclosed in Japanese Patent Application Laid-Open No. 55-60931 is bulky and correction of aberration is not satisfactory. The zoom lenses disclosed in Japanese Patent Application Laid-Open Nos. 8-334694 and 2002-6214 have a large number of lens elements and are difficult to be manufactured. Moreover, the zoom lenses disclosed in Japanese Patent Application Laid-Open Nos. 9-171140 and 2000-2837 have a large number of lens elements, so they are bulky.
Accordingly, no zoom lens disclosed in the above-described patent documents can reach a zoom lens system having small number of lens elements, high optical performance and compactness, and being easy to be manufactured.